Afon Alun
The river near Castle-upon-Alun
Location
Country	United Kingdom, Wales
Region	South Wales
County	Vale of Glamorgan
Physical characteristics
Source
• location	Llandow, Vale of Glamorgan, Wales
Mouth	Ewenny River
Length	7.2 km (4.5 mi)
Discharge
• location	Ewenny River

The Afon Alun is a river in the Vale of Glamorgan, south Wales. It is a tributary of the Ewenny River, which it joins to the south of Bridgend.^[1]

Course

Two streams join near Llandow village to form the river: the Stembridge Brook and the Llandow Brook. After the confluence it flows in a broadly north-westerly direction following the route of the Vale of Glamorgan railway until it joins the Ewenny River just upstream of Ogmore Castle.

The river has one tributary, the Colwinston Brook, which, joins the river near the village of Colwinston.